The goals of this project are the synthesis of short polynucleotides of known base sequence for the study of DNA-protein and DNA-drug interaction, and the improvement of the triester synthesis method of DNA synthesis. More specifically: a) We shall carry out x-ray structure analyses of high- and low-salt forms of CGCC (crystal data already collected), the complex of CGCC with cis-diaminodichloroplatinum(II) (small crystals obtained), and complexes of other tetramers such as GCGC, CCGG, GGCC, AATT, TTAA, and TATA with various intercalating drugs (DNA synthesized, crystals being grown). b) We shall begin crystallization trials with the DNA decamer: ATATCCATAT; CTATAGGTATA; to examine the structural parameters by x-ray diffraction of a complete turn of double helix, and to test ideas proposed by Sasesekharian about the instability of the CC base sequence. c) We shall continue to work on improvement of the triester method, focusing on better protecting groups and solid phase methods.